A conventional treadmill is shown in FIG. 7 and generally includes a frame 52 with a deck 54 connected between the two rails of the frame 52 and two rollers (not shown) are connected on two ends of the frame 52. An endless belt 53 reeves through the two rollers and one of the rollers is driven by a motor (not shown) so that the endless belt 53 moves at a desired speed. In order to reduce the friction between the deck 54 and the endless belt 53, a conventional lubrication device as shown in FIG. 8 is provided to feed lubricant between the deck 54 and the endless belt 53. The lubrication device includes a plurality of notches 541 defined in a top surface of the deck 54 and lubricant is filled in the notches 541 so that a layer of lubricant is established between the deck 54 and the endless belt 53. However, when the lubricant in the notches 541 needs to be refilled, the endless belt 53 has to be removed from the deck 54 of the frame 52 and this takes a lot of time and the customers cannot do the job well.
The present invention intends to provide a lubrication device for an endless belt of treadmills and the device includes a plurality of input tubes exposed on the outside of the frame so that the user can easily supply lubricant into the device without removing the endless belt from the frame.